Bioluminescent reactions are quite efficient, with quantum yields often approaching unity, in contrast with chemiluminescent processes, where chromophores may often easily oxidize by alternative "dark" processes. This proposal addresses the design and synthesis of an alkali-metal cation activated, allosteric device for mediating the chemiluminescence of typically bioluminescent chromophores. The device is modeled after aequorin, a calcium-activated photoprotein, which catalyzes the luminescence of coelenterazine and which has been extensively used as an indicator for intracellular free Ca2+. The target receptor can be tailored to be specific for either Na+ or K+. As there are currently no chemiluminescent assays for intracellular Na+ or K+ the device may see application in the study of cell processes. The first objective is the design of a receptor which will recognize coelenterazine, or a substituted derivative. The effects of this receptor on the chemiluminescent quantum yields of the bound chromophore will be determined. When the receptor has been optimized, it will be incorporated into an allosteric device, including a cation-binding site and a singlet oxygen sensitizer and/or source. Binding of a cation will trigger a conformational change, bringing the sensitizer and chromophore into close proximity, facilitating luminescent oxidation of the chromophore. The dependence of quantum yield on cation concentration will be determined.